[Lxc-users] loop mount inside container

[Marc Aymerich]

Dear all,
I'm trying to mount an image file inside a container but it complains
about write permissions:

(vct: container,
bestia: hw node)

root at vct:/dev# mount -o loop /root/server_bootable.img /mnt/
mount: block device /root/server_bootable.img is write-protected,
mounting read-only
mount: cannot mount block device /dev/loop1 read-only

root at vct:/# ls -al /dev/loop*
crw------- 1 root root 10, 237 Jun  4 14:52 /dev/loop-control
brw-rw---- 1 root disk  7,   0 Apr 26 17:10 /dev/loop0
brw-rw---- 1 root disk  7,   1 Apr 26 17:10 /dev/loop1
brw-rw---- 1 root disk  7,   2 Apr 26 17:10 /dev/loop2
brw-rw---- 1 root disk  7,   3 Apr 26 17:10 /dev/loop3
brw-rw---- 1 root disk  7,   4 Apr 26 17:10 /dev/loop4
brw-rw---- 1 root disk  7,   5 Apr 26 17:10 /dev/loop5
brw-rw---- 1 root disk  7,   6 Apr 26 17:10 /dev/loop6
brw-rw---- 1 root disk  7,   7 Apr 26 17:10 /dev/loop7

Write permissions to /dev/loop1 are provided through the container config file
lxc.cgroup.devices.allow = b 7:* rwm
lxc.cgroup.devices.allow = c 10:237 rwm

but in the end, I can't write to it:
root at vct:/dev# echo '' > /dev/loop1
-bash: echo: write error: Operation not permitted

writing to other loop devices seems possible:
root at vct:/dev# echo '' > /dev/loop2
-bash: echo: write error: No space left on device

I'm using ubuntu 10.04 with:

root at vct:/# uname -r
3.2.0-23-generic

root at bestia:/# lxc-version
lxc version: 0.8.0-rc1


Any idea about what the problem could be?

Thank you very much!!
-- 
Marc